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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 第一：定义数组
        var arr = [100,200,300] ;

        // 第二：使用数组
        console.log(arr[0]);
        console.log(arr[1]);
        console.log(arr[2]);
        
        







    </script>
</body>
</html>